The pks for Histidine are 1.8, 6.0, and 9.3. Of 100 molecules of Histidines at pH 6.0, how many are net positively charged? ● What is the ratio of uncharged to charged side chains at pH 7.0? Calculate the pl value of histidine.
Neutral Amino Acids
Amino acids which do not have any charge on them are neutral amino acids.
Globular Protein
The globular proteins refer to the shape of protein specifically spherical in nature apart from spherical form fibrous, disordered and membrane-bound proteins exist. These globular proteins are miscible in water and form a colloidal solution rather than other types which might not exhibit solubility. Many classes of the fold are found in globular proteins, which render them a sphere shape. Globular fold containing proteins usually are referred to by the term globin.
Dimer
Dimers are basic organic compounds, which are derivates of oligomers. It is formed by the combination of two monomers which could potentially be strong or weak and in most cases covalent or intermolecular in nature. Identical monomers are called homodimer, the non-identical dimers are called heterodimer. The method by which dimers are formed is known as “dimerization”.
Dipeptide
A dipeptide is considered a mixture of two distinct amino acids. Since the amino acids are distinct, based on their composition, two dipeptide's isomers can be produced. Various dipeptides are biologically essential and are therefore crucial to industry.
![## A Problem to Solve
**The pKs for Histidine are 1.8, 6.0, and 9.3.**
### Questions:
1. **Of 100 molecules of Histidines at pH 6.0, how many are net positively charged?**
2. **What is the ratio of uncharged to charged side chains at pH 7.0?**
3. **Calculate the pI value of histidine.**
### Diagram Explanation:
Below the questions, there is a detailed diagram showing the ionization states of histidine at different pH levels.
- **At pH < 1.8**: The structure of histidine shows:
- Amino group (\(NH_3^+\)) with a positive charge.
- Carboxyl group (\(COOH\)).
- Imidazole ring with a protonated nitrogen (\(NH^+\)), also having a positive charge.
- **Net charge = +2**
- **At pH = 6.0**: The structure of histidine shows:
- Amino group (\(NH_3^+\)) with a positive charge.
- Carboxyl group (\(COO^-\)) with a negative charge due to the loss of \(H^+\).
- Imidazole ring with a protonated nitrogen (\(NH^+\)), also having a positive charge.
- **Net charge = +1**
- **At pH = 9.3**: The structure of histidine shows:
- Amino group (\(NH_2\)) without a charge due to the loss of \(H^+\).
- Carboxyl group (\(COO^-\)) with a negative charge.
- Imidazole ring without a protonated nitrogen (\(N\)) without a charge.
- **Net charge = 0**
- **At pH > 9.3**: The structure of histidine shows:
- Amino group (\(NH_2\)) without a charge.
- Carboxyl group (\(COO^-\)) with a negative charge.
- Imidazole ring with a nitrogen (\(NH\)), without a charge.
- **Net charge = -1**
The graph is a reference guide showing the protonation states and net charges of histidine at different pH levels, which aids in answering the](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2F0253f3e8-444f-4de7-9704-1c8a253ee282%2F457da85e-4ece-4584-b22f-8ff9d8044718%2Fn5jwfv_processed.png&w=3840&q=75)
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